Cleaning is always good, I would only use abrasives and stay away from chemicals. Brake cleaner is a popular thing to use among gearheads to clean grease and grime from metal but if heated produces deadly gasses.

If you need it really clean, after you use flap disk on it you can either wipe it down with acetone (wife's nail polish remover, without her knowing it of course) or rubbing alcohol, which I use pretty often especially if I'm going to TRY to tig weld... But if I'm stickwelding or wire welding I just apply a flap disk to it breifly and then brush dust off with a clean wire brush... You can get it "too" clean for stick welding sometimes and you will know it if you do cause daggum rods will start to stick on you when you strike your arc like CRAZZZZZZY and cause you to use strong adjectives.